Sildenafil and Skin Cancer Risk

Jun 24, 2014

Scientists have discovered a possible link between the erectile dysfunction drug sildenafil and melanoma, a type of skin cancer.

But more research is needed and men should not make any changes to their medication regimens without talking to their healthcare providers first.

Sildenafil is the active ingredient in Viagra, which was approved by the U.S. Food and Drug Administration in 1998 for the treatment of erectile dysfunction.

Previous lab research showed that sildenafil had properties that might spur the growth of melanoma cells. This process could help these cancer cells spread elsewhere in the body.

With this in mind, the researchers decided to take a closer look at sildenafil and melanoma in men.

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They studied ten years’ worth of data (2000-2010) from men who participated in the Health Professionals’ Follow-Up Study, an ongoing research project that began in 1986. The men, all health professionals, were between 40 and 75 years old and completed health questionnaires every two years. In 2000, men were first asked whether they took sildenafil.

The analysis included information on 25,848 men with a mean age of 65 years. Just over 6% said they had used sildenafil at some point in their lives.

The researchers discovered that the men who took sildenafil had a higher risk of developing melanoma than the men who did not take the drug.

The study’s results need to be interpreted carefully, however.

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As Harvard Men’s Health Watch Executive Editor Daniel Pendick explains in this post from the Harvard Health Blog, 4.3 out of every 1,000 men in this study who didn’t take Viagra developed melanoma. And 8.6 out of every 1,000 men whodid take Viagra also developed melanoma.

After statistical adjustments are made, this shows that the risk increases 84% from one group to the other.

That sounds like a lot. However, this percentage refers to relative risk. Relative risk applies only to two specific groups – in this case, the men who didn’t take Viagra and those who did in this particular study.

When discussing studies like this one, looking at absolute risk is more helpful. Absolute risk is the risk of developing an illness over time. In this case, the risk increases by 4.3 cases in every 1,000 men or 0.43%.

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In other words, in a group of 1,000 men who took Viagra, 8.6 would have an increased risk of developing melanoma, according to this study.

It’s also important to remember that many factors raise a person’s risk for melanoma, such as the following:

· Fair or freckled skin

· Light-colored hair

· Too much ultraviolet (UV) light exposure (such as from the sun or tanning beds)

· Moles

· Family history of melanoma

· Weakened immune system

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The results of this study do not mean sildenafil causes skin cancer. Nor do they mean that there is a link between erectile dysfunction and skin cancer. Instead, they give more information about these two groups of men and provide a jumping-off point for future research.

Before any health recommendations can be made, scientists will need to conduct more research to see if they get similar results. They may also decide to research other erectile dysfunction drugs and their relationship to melanoma. (Drugs like

tadalafil (Cialis) and vardenafil (Levitra) were not included in this study, as they had not yet been approved when the research began.)

Men are encouraged to talk to their doctors with any concerns they have about erectile dysfunction or melanoma.